The invention concerns a method for determining the fat content in samples, preferably organic samples, for example foodstuffs. Due to the legal requirements with regard to the stating of contents in the case of foodstuffs, the determination of fat content is of increasing significance. From the point of view of the physiology of nutrition, the detection of the total fatty acids contained by a food product is of interest: only the determination of fat content on the basis of fatty acids will enable a definitive assessment of the fat calorific value of foodstuffs.
A state of the art method for the determination of fat is based on extraction of fat from the sample with the aid of an organic solvent. Here, for example, direct extraction according to Soxhlet can be mentioned. Extraction after disintegration by means of either an acid or a base (Webull-Stoldt, Rose-Gottlieb) is also known. All these classic methods have various disadvantages. In the main, they are relatively complicated and time-consuming in their application, and are suited only to the determination of fat content in a particular kind of sample. A disadvantage common to all these methods is that the fat is not determined on the basis of fatty acids. Thus, from the point of view of the physiology of nutrition, no definitive results can be obtained.
Methods are also known where the fat portion extracted from the sample is separated into the fatty acids corresponding to the fat by means of saponification and subsequent acidification. These fatty acids are esterified and determined by means of chromatography. In this way, the proportion of each fatty acid within the total fat content can be determined. The disadvantage of this method is that it requires many working steps, With determination being achieved only after a long period of time. In addition, it is not necessary to know the distribution of individual fatty acids when determining the total fat content of foodstuffs. Apart from that, with this state of the art extraction method, the fats are not selectively extracted from the sample.